Would be nice if while they're at it they let us migrate our message history between iOS/Android properly. The paid 3rd party solution I used didn't work, by the time I was done messing with it I'd already been using Whatsapp for a week and had to value the new history over the old and not risk wiping it out.
I don't know about iOS, but in Android it saves everything to Google drive. So you can buy a new phone and have whatsapp fully restored within minutes. I guess they would have that functionality on iOS too.
Yes it works fine on the same OS, there's a backup/restore option. Swapping between the two vendors isn't supported. I think the excuse is encryption keys however it's not insurmountable if they want to make it work (some 3rd party solutions do work, I think my large archive was just breaking the one I chose, they sent me a debug build but I had more issues so gave up).
